So, as many things do in life, this started off as just a fuzzy sound reactive hat.
... alright, well maybe only a few things start off as a fuzzy sound reactive hat, but this was certainly one of them. It's got a mic in there for this video and I think thats it besides the blinkies.
Later on I added a 7 channel equalizer chip and an accelerometer and did some preliminary beat detection for dancing.
It turns out beat detection is like a whole THING that is pretty hard to do, though, perhaps things have changed since I last looked at it.